Evaluation of a Natural Phytogenic Formulation as an Alternative to Pharmaceutical Zinc Oxide in the Diet of Weaned Piglets

SIMPLE SUMMARY: Post-weaning diarrhea in piglets is caused by intestinal dysbiosis, characterized as an undesirable disruption of the physiological intestinal microbiota, which is associated with several stress factors, such as the isolation of piglets from sows, the adaptation to new environment and morphological changes in the intestine due to the transition from milk to solid feed intake. Pharmaceutical zinc oxide has been effectively used to alleviate these effects. However, since the dietary supplementation with pharmaceutical doses of zinc oxide (ZnO) in weaning pigs has been recently phased out in EU, this study aimed to determine the effect of a natural phytogenic formulation on growth performance, nutrient digestibility and faecal microbiota composition and metabolic activity. Dietary inclusion of the natural phytogenic formulation significantly increased piglet performance and nutrient digestibility and reduced the E. coli and C. perfringens counts as well as the molar ratios of branched chain volatile fatty acids in faeces. In summary, the results of this study indicate that the tested natural phytogenic formulation could be considered as an effective alternative to pharmaceutical doses of ZnO to alleviate the challenges commonly occurring after weaning. ABSTRACT: A natural phytogenic formulation (NPF) was tested as an alternative to pharmaceutical zinc oxide (ZnO) in weaned piglets with respect to growth performance, apparent total tract digestibility and faecal microbiota composition and metabolic activity. Two dietary NPF levels (NPF: 1000 and 2000 mg/kg diet) were compared to a positive control (ZnO: 3000 mg ZnO/kg diet) and a negative control (CON: no added ZnO or NPF) using 84 weaned piglets from 29 d to 78 d (days of age). Feed conversion ratio was improved (p < 0.05) in ZnO and NPF piglets were compared to CON at 50 d. Dry matter, organic matter and crude protein (p < 0.05) digestibility was improved in NPF piglets compared to CON at 57 d. Compared to CON, NPF inclusion reduced E. coli (p < 0.05) and increased C. leptum subgroup (p < 0.01) at 57 d and 78 d, and reduced C. perfringens subgroup (p < 0.05; at 78 d). The ZnO reduced (p < 0.001) E. coli and C. perfringens subgroup (p < 0.01) compared to CON at 78 d. Moreover, ZnO and NPF reduced molar ratios of branched chain volatile fatty acids (p < 0.05) compared to CON, while NPF also increased butyric acid (p < 0.05) at 78 d. In conclusion, the NPF appeared to be a promising alternative to pharmaceutical doses of ZnO.